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Research On Parallel Control Strategy Of Modular Phase-Shifted Full-Bridge DC-DC Converters

Posted on:2022-02-25Degree:MasterType:Thesis
Country:ChinaCandidate:Y H ZhouFull Text:PDF
GTID:2492306512971299Subject:Power electronics and electric drive
Abstract/Summary:PDF Full Text Request
In recent years,with the rapid development of electric vehicles,aerospace,data centers and electrochemical processing,it has a bigger demand for high-power DC power supplies.Although multiple DC power supplies in parallel can meet the requirements of different capacities,current sharing control among power supplies is crucially important.Thus,the phase-shifted full-bridge(PSFB)DC-DC converter is selected as a basic module unit.The control strategy for the basic module and current sharing control strategy for modules in parallel are studied to make the DC power supply system in parallel meet the demand of rapid load changes.At the same time,good current sharing performance can be achieved.The main research contents of this thesis are as follows:Firstly,the operating principle of the PSFB DC-DC converter in continuous current mode(CCM)is introduced and the state-space average model of the PSFB DC-DC converter is established.The output current rapid response control method based on the predictive current control is studied.Aiming at the problem of the duty cycle loss in the secondary side for PSFB DC-DC converter,duty cycle compensation is introduced to improve the accuracy of the predictive current model.An integral compensation is introduced to eliminate the steady-state error of output current caused by the parasitic parameters of the converter,thereby the improved predictive current control(IPCC)is obtained.The filter inductance parameter sensitivity analysis of predictive current control is presented.The effectiveness of the IPCC method is verified by building the PSIM simulation model of the single-module PSFB DC-DC converter.Secondly,the shortcomings of the parallel system including modular PSFB DC-DC converters under the traditional droop control method are analyzed.Aiming at the mutual interaction among the quality of output voltage,the accuracy of current sharing and the circulating current in consideration of the line impedance,a coordinated control strategy based on adaptive droop characteristics in this thesis is studied.By introducing the output voltage compensation,the output current compensation and the circulating current suppression strategy,the traditional droop control is improved to achieve the accuracy of current sharing,the quality of output voltage,the circulating current suppression and the dynamic performance improvement.And the stability of the parallel system under coordinated control strategy based on adaptive droop characteristics is analyzed,which shows that the system can always operate stably.The correctness of the coordinated control strategy is verified by building the PSIM simulation model of the parallel system composed of the modular PSFB DC-DC converters.Finally,the experimental platform is built to verify IPCC strategy and the coordinated control strategy based on adaptive droop characteristics under various working conditions.Compared with the traditional output current control,IPCC method can enhance the anti-interference and dynamic response speed of the single-module PSFB DC-DC converter under various working conditions,and the dynamic performance of the converter can be effectively improved.The experimental results show that the parallel system using coordinated control strategy based on adaptive droop characteristics can quickly restore the output voltage under mutation conditions and improve the steady-state bus voltage quality and current sharing accuracy,and the parallel system has excellent dynamic current sharing performance.The feasibility of the control strategy studied in this thesis is confirmed.
Keywords/Search Tags:Phase-shifted full-bridge DC-DC converter, Improved predictive current control, Current sharing control, Adaptive droop characteristics
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